Accurately timed gestations in Rhesus monkeys are used. Streptozotocin, 40-48 mg/kg is administered intravenously to the adult female prior to or in the first trimester of pregnancy. This drug induces a glucose intolerant state secondary to pancreatic beta cell destruction. During the third trimester, acute experiments are performed under general anesthesia and aseptic surgical techniques. Cannulae are placed into both the maternal and fetal circulations to permit sequential sampling of blood. The responsiveness of the pancreatic cells to beta adrenergic agents as well as to somatostatin are examined by obtaining blood aliquots and analyzing them for glucose, insulin, growth hormone, and glucagon using biochemical and radioimmunoassay procedures. In some instances the same experiment in the newborn is performed on the first day of life after which tissue is examined histologically from both mother and conceptus.